A global assessment of glyphosate and AMPA inputs into rivers: Over half of the pollutants are from corn and soybean production.

ABSTRACT

Glyphosate is widely used in agriculture for weed control; however, it may pollute water systems with its by-product, aminomethylphosphonic acid (AMPA). Therefore, a better understanding of the flows of glyphosate and AMPA from soils into rivers is required. We developed the spatially explicit MARINA-Pesticides model to estimate the annual inputs of glyphosate and AMPA into rivers, considering 10 crops in 10,226 sub-basins globally for 2020. Our model results show that, globally, 880 tonnes of glyphosate and 4,090 tonnes of AMPA entered rivers. This implies that 82 % of the river inputs were from AMPA, with glyphosate accounting for the remainder. Over half of AMPA and glyphosate in rivers globally originated from corn and soybean production; however, there were differences among sub-basins. Asian sub-basins accounted for over half of glyphosate in rivers globally, with the contribution from corn production being dominant. South American sub-basins accounted for approximately two-thirds of AMPA in rivers globally, originating largely from soybean production. Our findings constitute a reference for implementing and supporting effective control strategies to achieve Sustainable Development Goals 2 and 6 (food production and clean water, respectively) simultaneously in the future.